I just recently bought the 5900 SQ Sumo, and had a different shaft put on it (cant remember off hand).
I'm still getting used to it, but each round I seem to be getting a little more consistent. I wouldnt say the driver is longer than other drivers I've played or tested (including the Dymo), but the ball does seem to go straighter a little easier.
But one thing I've learned with all my clubs (I upgraded from crappy clubs to very good ones recently after saving for a long time for them), is that if you make a bad swing your going to get a bad result, I dont care what kind of driver, iron or wedge you hit.
IF, I had to do it all over again, I probably would've paid the extra money and bought the DYmo St8-Fit. The large square face (at least right now) has me overthinking a little bit, and possibly even overconfident that I dont focus on making a great swing.
But the 5900 Sumo was less than half the price. Hopefully I"ll continue to get longer and more consistent with it.